Do I need to buy another battery to run my lowrance active target, hds 9 live,Elite FS 9? I have them on with my cranking battery.
You should also say WHAT BATTERY you have! If it's a dink, then yes, you need a new plan. If you have a large main battery, then no, you should be fine if you manage power use.
So far, I run four 12" Lowrance units and will be adding an Active Target soon. I have a honkin' AGM Group 31 battery for the main battery (everything but trolling motor).
When you leave the console to go to the bow (and in the opposite direction) be sure to use SLEEP MODE. This will cut power use dramatically for whichever unit you aren't looking at anyway. The units will return to active almost instantly when you push the power button to take them out of sleep - they do not need to reboot.
Your Active Target has a software bug. It will turn on via sensing a powered unit connected to the yellow wire, but it will NOT turn off when the connected display does. This will be fixed in a future software release. Because of the bug, you may be burning power unnecessarily. I rig A. T. via switched power (switch at the console). That way, when I sit down to run on plane (or any other time I want) I can turn off the Active Target module to save power.
No matter how careful we may be, there's always a chance a battery will fail, so it's best to be prepared. I carry an adequate Lithium jump-starter module in my truck, and move it to the boat as part of my launch preparation. It will start a 6.2L gas engine, so it will certainly jump my outboard.